1. Field of the Invention
The present invention generally relates to image forming devices, such as copiers, facsimiles and printers, and more particularly to an image forming device the maintenance of which can be remotely managed by a central management equipment by using a communication line.
2. Description of the Related Art
Image forming devices that perform image formation on paper by using an electro-photoconductive printing process are commonly known. The rate of occurrence of a malfunction in the mechanism that carries out the electro-photoconductive printing process is comparatively high. Moreover, there is the necessity for periodical inspection of the image forming devices for performance maintenance, and the service organization of the maintenance must be provided. For example, in order to perform a periodical use situation report and an operation quality check to the customer (user) who purchased an image forming device, it is necessary for the central management equipment to acquire periodically the state information which indicates the state of the image forming device.
For the purpose of efficient maintenance, the image forming device of a certain type is equipped with a communication device that is connectable with a central management equipment, installed at a remote service center, via a communication line, such as a telephone line (public line). The image forming device is periodically connected with the central management equipment through the communication line by using the communication device. By performing the communication, the image forming device periodically sends a regular message to the central management equipment. The state information is contained in the regular message, sent to the central management equipment via the communication line, and it indicates the operational states of the image forming device concerned (for example, the lapsed period from the time of installation of the device concerned, the total number of copy sheets used, the period of use of the device concerned, etc.).
Moreover, when a malfunction occurs, the image forming device is connected with the central management equipment through the communication line by using the communication device. By performing the communication in such situations, the image forming device sends an irregular message to the central management equipment. For example, the irregular message is sent to the central management equipment when a malfunction phenomenon (self-diagnostic abnormalities) or a preliminary malfunction phenomenon (prior warning) takes place in the image forming device. The malfunction information is contained in the irregular message, and it is notified to the central management equipment. The timing of an irregular message is not predictable.
However, with the use of the image forming devices which transmit the regular message and the irregular message, there is the case where the sending of such messages to the central management equipment is performed very frequently, and the amount of the messages or the traffic from the image forming devices to the central management equipment exceeds a permissible level. It may cause a trouble in the communication environment that is originally provided for the image forming devices. Moreover, it may cause a difficulty in performing the maintenance management of the image forming devices by the central management equipment.